1. Field of the Invention
The present invention relates to a method for rapidly identifying porcine insulin-like-growth factor 2 intron 7 point mutation (IGF2-in7-C162G) and, more particularly, to use a method for sorting stud pigs by IGF2-in7-C162G genotypes.
2. Description of the Related Art
Pigs are valuable livestock and improvement in the stud pigs for enhancing productivity is important to those who breed pigs at high costs. Conventional ways of sorting stud pigs by shapes have reached a bottleneck. On the other hand, rapid development in molecular biological techniques focusing on sorting of genes controlling growth characteristics has allowed putting various genes advantageous to productivity in a single animal, thereby enhancing the efficiency and accuracy in stud pig selection. A method named “Auxiliary Sorting of Inheritance Marker”, which combines molecular biological techniques and quantity inheritance assessing theory for strategic gene sorting, is particularly useful in sorting out propagating characteristics with low inheritance variation and carcass characteristics requiring high assessing costs. An example for identifying stud pigs with high reproductive potential is disclosed in U.S. Pat. No. 6,846,632, which teaches a method for rapidly identifying porcine estrogen receptor marker by mutagenically separated polymerase chain reaction (MS-PCR).
Besides productivity, another value index for pigs is the quality of meat production, which is the primary index for the production effect of livestock. Selection of male stud pigs aiming to increase the muscle mass of domestic pigs and to improve the lean meat percentage of carcass is the common goal to the pig breeding industry and the carcass processing industry. Meat quality and meat quantity are controlled by multiple genes. However, literatures on the genes and the interaction among various genes are scarce.
Only few references discussed genes regarding carcass characteristics of meat production quantity and quality of pigs; these genes include stress gene (Fujii et al., 1991), acid meat gene (R N, Ciobanu et al., 2001; Milan et al., 2000), MC4R gene (Kim et al., 2000), and insulin-like-growth factor 2 (IGF2) gene (van Laere et al., 2003).
The protein of IGF2 affects growth of cells. The porcine IGF2 gene is located on 2pl.7 of the second chromosome. The gene is 23,821 base pairs in length and is composed of four promoters, ten exons, and nine introns.
According to research results, the single nucleotide polymorphism (SNP) in IGF2-in3-G3072A of pigs is a quantitative trait nucleotide (QTN) that mainly affects quantitative trait of muscle quantity and fat accumulation of pigs. Thus, A allele in the IGF2-in3-3072 position is accompanied by the characteristics of high muscle quantity and low fat accumulation (Jeon et al., 1999; Nezer et al., 1999; van Laere et al., 2003; Jungerius et al., 2004). However, Detection of the polymorphism utilizes real-time polymerase chain reaction (Carrodeguas et al., 2005) or minisequencing (SnaPshot, Vykoukalova et al., 2006). The procedures are complicated and inefficient; therefore, improvement is required.